Spatial coordination strategies in future ultra-dense wireless networks

Ultra network densification is considered a major trend in the evolution of cellular networks, due to its ability to bring the network closer to the user side and reuse resources to the maximum extent. In this paper we explore spatial resources coordination as a key empowering technology for next generation (5G) ultra-dense networks. We propose an optimization framework for flexibly associating system users with access nodes in a densely deployed network, opting for the exploitation of densification and the control of overhead signaling. Combined with spatial precoding strategies, network resources management approaches are designed, reflecting various features, namely local vs. global channel state information knowledge exploitation, centralized vs. distributed implementation, and non-cooperative vs. joint multi-node data processing. We apply these strategies to future dense network setups, and explore the impact of critical network parameters, that is, the densification levels of access nodes, the density of users requesting service, and the power budget constraints. We demonstrate that spatial resources coordination is a key factor for capitalizing on the gains of ultra dense network deployments.